Low Levels of Vitamin D in Patients With Bipolar Disorder

Approximately 2.5% of people worldwide are estimated to have bipolar spectrum disorders, which are a significant cause of neuropsychiatric disability.

Over the years, researchers have pointed to a potential link between vitamin D deficiency and neuropsychiatric illness, including major depressive disorder and schizophrenia. A new report provides further evidence that confirms the association between low vitamin D and bipolar disorder. A group of Dutch researchers published their findings in the Journal of Clinical Psychopharmacology.

It is estimated that 1 billion people have insufficient levels of vitamin D due to poor diet and a lack of exposure to sunlight. Also, increased prevalence of vitamin D deficiency has been reported in individuals who suffer from serious, chronic psychiatric conditions such as schizophrenia and depression. Until now, however, the evidence of vitamin D deficiency among patients who are diagnosed with bipolar disorder is limited.

For the current cross-sectional study, researchers recruited 118 adults from an outpatient clinical for bipolar disorder. They also included patients diagnosed with schizophrenia (n=149) or schizoaffective disorder (n=53). Their main aim was to assess whether low vitamin D levels were more prevalent among outpatients with psychiatric conditions than among the general Dutch population, and to compare the prevalence of vitamin D deficiency between outpatients with bipolar disorder, schizophrenia, or schizoaffective disorder.

Optimum vitamin D levels were classified as higher than 30 ng/ml, and 12 ng/ml or lower was considered deficiency in vitamin D levels. In a linear multiple regression analysis, investigators used age, sex, ethnicity (yes or no white), time of assessment (summer or not), and diagnosis (bipolar or not) as predictors. The concentration of S-25OHD was used as a dependent variable.

Results indicate that more than 30% of participants in the sample had low (ie, deficient) vitamin D levels (95% CI, 25.5-35.6), while less than 15% of individuals had optimal levels of vitamin D (95% CI, 10.9-18.7). Vitamin D deficiency was recorded in more than 22% of patients with bipolar disorder (95% CI, 16.2-31.3) and in almost 35% of patients with schizophrenia or schizoaffective disorder (95% CI, 28.4-41.5). There was a significant absolute difference in vitamin D deficiency between the primary study population and the Dutch white population, with study participants having almost 25% lower vitamin D levels (95% CI, 18.3-29.3).

Although the type of psychiatric disorder was not a predictor of low vitamin D levels, present results are in line with previously reported findings and show that “vitamin D deficiency was found to be 4.7 times more common in a population of 320 outpatients with bipolar disorder, schizophrenia, or schizoaffective disorder compared with the Dutch general population,” the authors wrote. Researchers suggest that these patient populations should be regularly screened for vitamin D deficiency, which “may constitute an Underrecognized health risk to outpatients with bipolar disorder, schizophrenia, or schizoaffective disorder."